The present invention relates to a process for the utilization of a fuel, a product obtainable by the process according to the invention, the use of the product, and a device for producing a mixture for use in the process according to the invention.
Modern low-pollution methods for the combustion of gaseous, liquid and solid fuels share a common constructional feature: a technically sophisticated generation of the mixture. The formation of the mixture is a critical criterion of the quality of combustion. Inhomogeneities of any kind, e.g., distribution of the fuel/oxidant in a combustion chamber, generally result in the formation of pollutants. When the mixture is locally poor in oxygen, unburnt hydrocarbons and carbon black can occur as a consequence of incomplete combustion.
These findings have already resulted in the development of premixing combustion systems. For gaseous fuels, the formation of a mixture with oxygen or air is less complicated. Therefore, improvements could be achieved early in this case.
The formation of a mixture between air and liquid fuels is more complicated to realize technically than for gaseous fuels. There are various ways to produce a homogeneous mixture. The systems involve atomization of the liquid and/or thermal treatment which results in a partial or complete vaporization in the air or exhaust gas.
In middle distillates, designs for the evaporation of liquid films, running down hot surfaces, for example, over extended periods of time raise the problem of formation of depositions on the surfaces of the evaporator. This has been described in various papers, including Brand et al. (1981), Kostka et al. (1982) and Mallog et al. (1983). The depositions are reaction products from cracking reactions occurring at temperatures of above 400xc2x0 C. However, such high temperatures up to above the final boiling point of the middle distillate (380xc2x0 C. to 400xc2x0 C.) are required for a sufficient heat transfer from the evaporator wall to the liquid medium. The depositions lead to a deterioration of heat transfer and thus to fault liability of the system. To avoid the formation of depositions, contact of the liquid fuel with hot walls must be avoided.